The predictive role of Interleukin 6 in burn patients with positive blood cultures

Interleukin 6 (IL-6) is an established biomarker of inflammation with one of the earliest responses in sepsis. Serum levels can easily be measured within a few hours. The clinical significance of IL-6 in the early stage of sepsis in burned patients has not yet been confirmed. The purpose of our research was to investigate the predictive value of IL-6 for positive blood cultures in comparison to Procalcitonin (PCT), white blood cell (WBC) count, body temperature and the Sequential Organ Failure Assessment (SOFA) score in the presence of suspected sepsis in burn patients. In a retrospective study, we included all patients admitted to a regional burn centre in a 7-year period. Patients with a clinical suspicion of sepsis and complete laboratory tests underwent further analysis. Patients were categorized following culture results into either positive or negative bloodstream infection (BSI or non-BSI) groups. 39 of the 101 included patients had positive blood cultures (BSI). The serum IL-6 levels were significantly higher in the BSI group [1047 (339.9; 9000.5) vs. 198.5 (112.4; 702.5) ng/l; P = 0.001]. Receiver operating characteristic (ROC) curve analysis showed an AUC of 0.7 (59; 80.8%). The optimal IL-6 cut-off level was 312.8 ng/l (sensitivity 79.5%, specificity 56.5%). Other biomarkers (PCT, WBC), the maximum body temperature and increase of SOFA score were not different between the groups. IL-6 can be used to predict a positive blood culture even in the early stage of suspected sepsis in burned patients. In this context, other biomarkers (PCT, WBC) and body temperature are of limited clinical utility.